In mammalian veins, venous valves are positioned within portions of the vessel in the form of leaflets disposed annularly along the inside wall of the vein which open to permit blood flow toward the heart and close to prevent back flow. These venous valves open to permit the flow of fluid in the desired direction, and close upon a change in pressure, such as a transition from systole to diastole. When blood flows through the vein, the pressure forces the valve leaflets apart as they flex in the direction of blood flow and move toward the inside wall of the vessel, creating an opening in between for blood flow. The leaflets, however, do not normally bend in the opposite direction and therefore return to a closed position to restrict or prevent blood flow in the opposite, i.e. retrograde, direction after the pressure is relieved. The leaflets, when functioning properly, extend radially inwardly toward one another such that the tips contact each other to block backflow of blood. The competence of venous valves can be degraded or reduced if the leaflets do not adequately contact each other.
Disabling of incompetent venous valves can be performed for various reasons. For example, disabling of incompetent venous valves can be performed prior to implantation of a venous valve prosthesis. Venous valves may also be disabled within a section of vein used as a graft for surgical implantation at another site, where venous valves are often removed or disabled prior to implantation of the graft. Procedures such as in a coronary artery bypass grafting (CABG) commonly use vein segments with disabled or disrupted venous valves.
There are several procedures known in the art for disabling venous valves. Valvulotome devices are often used to render native venous valves incompetent. Several mechanical valvulotomes have been devised to date to cut valves in veins. The most common valvulotome in use is the mechanical valvulotome, which is an instrument with cutting edges specially designed to be passed into veins to cut the valves mechanically.
One disadvantage of the mechanical valvulotome is the possibility of injury to the walls of the vein. Moreover, there is the possibility that a valve could be missed since the valvulotome could slip past the valve. This potential problem is of major concern as it would lead to intraoperative angiograms and increased length of the primary surgical procedure.
Preferred valvulotome devices described herein have one or more cutting edges oriented in a manner that reduces potential injury to the walls of the vein. Furthermore, some embodiments provide valvulotome device embodiments comprising structural features adapted to slidably engage a venous valve leaflet. Related delivery devices and kits, as well as methods for using the same, are also provided by embodiments described herein.